Glass sheet roller conveyor furnace including gas jet pump heating

Abstract

A roller conveyor furnace (12) is disclosed as including at least one gas jet pump (24) for providing forced convection heating of glass sheets during conveyance on rolls (22) of the furnace conveyor (20). A source (26) of compressed gas located externally of the furnace is communicated with the gas jet pump to supply a primary gas flow thereto and induce an amplified extent of a secondary gas flow in order to provide a combined flow of heated gas that produces the forced convection heating. Upper and lower arrays (70,72) of the gas jet pumps are disclosed as being usable separately or in cooperation with each other in one embodiment to maintain temperature uniformity and glass shet planarity. Each array includes an associated conduit support (74,76) that mounts the gas jet pumps thereof in a spaced relationship transverse to the direction of conveyance either above or below the conveyor rolls. In another embodiment , the compressed gas supplied to the gas jet pumps (24) is heated to provide the primary source for heating the furnace. One gas jet pump utilized comprises a simple jet opening, while another pump comprises a restricted opening and a contoured surface along which the primary gas flow is guided, and a further pump includes a deflector that initially guides the primary gas flow from a restricted opening along the contoured surface.

What is claimed is: 
     
       1. A glass sheet heating furnace comprising: a housing defining a heating chamber, a roller conveyor including horizontally extending rolls for conveying glass sheets horizontally through the heating chamber for heating thereof, a plurality of gas jet pumps spaced along the length of the conveyor within the heating chamber, a source of compressed gas located externally of the heating chamber and communicated with the gas jet pumps to supply a primary gas flow thereto, a heater for heating the compressed gas supplied by said source to the gas jet pumps to provide the primary source for heating the furnace, said primary gas flow inducing a secondary gas flow and providing a combined flow of heated gas, and said gas jet pumps being oriented such that the combined flow of heated gas therefrom is directed toward the conveyor to provide forced convection heating of conveyed glass sheets during conveyance thereof on the rolls of the conveyor with the bottom glass sheet surfaces in continuous engagement with the conveyor rolls. 
     
     
       2. A furnace as in claim 1 which includes upper and lower arrays of the gas jet pumps spaced along the length of the conveyor, conduit supports that mount the gas jet pumps of the arrays, and insulation that surrounds each gas jet pump to prevent radiant heating of conveyed glass sheets by the conduit supports. 
     
     
       3. A glass sheet heating furnace comprising: a housing defining a heating chamber; a roller conveyor including horizontally extending rolls for conveying glass sheets horizontally through the heating chamber for heating thereof; arrays of gas jet pumps spaced along the length of the conveyor within the heating chamber; each array including a plurality of gas jet pumps spaced from each other transversely to the direction of conveyance; a source of compressed gas located externally of the heating chamber; a heater for heating gas supplied by the compressed gas source; conduit supports that mount the arrays of gas jet pumps within the heating chamber and provide communication thereof with the compressed gas source to supply a primary gas flow of heated gas to the pumps in order to provide the primary source of heating the furnace; said primary gas flow inducing a secondary gas flow to provide a combined gas flow of heated gas; and said gas jet pumps being oriented such that gas flow therefrom is directed toward the conveyor to provide forced convection heating of conveyed glass sheets during conveyance thereof on the rolls of the conveyor with the bottom glass sheet surfaces in continuous engagement with the conveyor rolls. 
     
     
       4. A furnace as in claim 3 further including insulation that surrounds the gas jet pumps to prevent radiant heating of the conveyed glass sheets by the conduit supports, and the gas jet pumps projecting from the insulation toward the conveyor. 
     
     
       5. A glass sheet heating furnace comprising: a housing defining a heating chamber; a roller conveyor including horizontally extending rolls for conveying glass sheets horizontally through the heating chamber for heating thereof; upper and lower arrays of gas jet pumps spaced along the length of the conveyor within the heating chamber above and below the roller conveyor; each array including a plurality of gas jet pumps spaced from each other transversely to the direction of conveyance; a source of compressed gas located externally of the heating chamber; a heater for heating gas supplied by the compressed gas source; upper and lower conduit supports that respectively mount the gas jet pumps of the upper and lower arrays and provide communication thereof with the compressed gas source to supply a primary gas flow of heated gas to the pumps in order to provide the primary source of heating the furnace; said primary gas flow inducing a secondary gas flow to provide a combined gas flow of heated gas; each gas jet pump including a jet opening that is fed the heated and compressed gas; said gas jet pumps of the upper and lower arrays being oriented such that gas flows therefrom are respectively directed downwardly and upwardly toward the top and bottom surfaces of conveyed glass sheets to provide forced convection heating thereof during conveyance of the glass sheets with the bottom surfaces thereof in continuous engagement with the conveyor rolls; and insulation that surrounds the gas jet pumps to prevent radiant heating of the conveyed glass sheets by the conduit supports, and the gas jet pumps of each array projecting from the insulation toward the conveyor. R